Background: Numerous studies have examined the association between adolescents’ marijuana use and their high-risk sexual behaviors and sexually transmitted diseases (STDs). However, the validity of the findings is questionable because most of the studies relied on self-reporting for measurement of marijuana use and key outcome (i.e., STDs).
Goal: The goal was to investigate associations between biologically confirmed marijuana use and laboratory-confirmed STDs and condom use.
Study Design: African American females adolescents (n = 522) completed a self-administered survey and face-to-face interview. The adolescents provided urine and vaginal swab specimens that were analyzed for marijuana metabolites and STDs, respectively.
Results: Among the study subjects, 5.4% tested positive for marijuana. These adolescents were more likely to test positive for Neisseria gonorrhoeae (adjusted odds ratio [AOR] = 3.4) and Chlamydia trachomatis (AOR = 3.9). They were more likely to have never used condoms in the previous 30 days (AOR = 2.9) and to have not used condoms consistently in the previous 6 months (AOR = 3.6).
Conclusion: The findings represent unique biologic evidence that STDs and sexual risk behavior may co-occur with marijuana use. Interventions designed to reduce adolescents’ risk of STDs and HIV infection should address marijuana use.
Among 522 African American adolescent females, those who tested positive for marijuana were more likely to be laboratory-confirmed-positive for STDs and to have a higher prevalence of STD-associated sexual behaviors.
From the *Rollins School of Public Health, Department of Behavioral Sciences and Health Education, and the †School of Medicine, Department of Pediatrics (Division of Infectious Diseases, Epidemiology and Immunology), Emory University, Atlanta, Georgia; ‡Emory/Atlanta Center for AIDS Research, Atlanta, Georgia; and §Department of Pediatrics and ∥Department of Medicine (Division of Infectious Diseases), School of Medicine, and ¶Department of Health Behavior, School of Public Health, University of Alabama, Birmingham
The authors thank Jane R. Schwebke (University of Alabama at Birmingham School of Medicine, Division of Infectious Diseases) for provision of cultures for Trichomonas vaginalis and Kim Smith, MT (ASCP), for assistance and oversight of testing for Neisseria gonorrhoeae and Chlamydia trachomatis.
Supported by a grant from the Center for Mental Health Research on AIDS, National Institute of Mental Health (IR01 MH54412), and a supplement from the National Institute of Drug Abuse to the second author.
Reprint requests: Ralph J. DiClemente, PhD, Rollins School of Public Health of Emory University, 1518 Clifton Road NE, BSHE/Room 554, Atlanta, GA 30322. E-mail: firstname.lastname@example.org
Received for publication June 29, 2001,
revised October 22, 2001, and accepted October 29, 2001.
AFRICAN AMERICAN ADOLESCENT FEMALES have been disproportionately affected by substance use 1 and sexually transmitted diseases (STDs). 2,3 Prevention efforts tailored for this population constitute a national priority. 2,4,5 Prevention programs are especially important for female adolescents residing in low-income neighborhoods with a high prevalence of violence, teen pregnancy, HIV/STDs, and substance abuse. 6
Previous investigations have shown that adolescents’ substance abuse and sexual behaviors may be associated forms of risk behavior. Bailey et al 7 found that among homeless youths, marijuana use during the most recent sexual encounter was associated with nonuse of condoms. Duncan et al 8 found significant associations between the use of marijuana, cigarettes, and alcohol and risky sexual behavior. Kingree et al 9 found that marijuana use was related to infrequent condom use among adolescent detainees. Although these studies provided valuable information, they were limited by the use of adolescents’ self-reports to assess marijuana use and high-risk sexual behaviors and STDs.
Only a few studies have employed biological assessments to investigate associations between adolescents’ substance abuse and their sexual risk behaviors. Tengia-Kessy et al 10 found that among male adolescents, self-reported use of marijuana was one of several significant risk factors associated with an increased likelihood of testing positive for HIV. Boyer et al 11 found that African American adolescents who self-reported marijuana use were more likely to test positive for STDs. Although one advantage of these studies is their inclusion of a biologically assessed outcome (i.e., STDs or HIV), they were limited by the reliance on adolescents’ self-reported marijuana use. In addition, most of the studies did not focus specifically on African American adolescent females. Given the scarcity of ethnic- and gender-specific substance use prevention programs tailored toward African American adolescent females and the disproportionate impact of the STD and HIV epidemic on this population, additional research addressing the association between marijuana use and high-risk sexual behaviors and STDs among this population is warranted. 12
The current investigation examined associations between biologically assessed marijuana use and laboratory-confirmed STDs, as well as risky sexual behaviors, among African American female adolescents. As opposed to studies that relied on adolescents’ self-reported marijuana use, the current study used a well-established laboratory assay to ascertain the presence of marijuana use. 13 In addition, the study was restricted to female adolescents with steady partners, because evidence suggests that safer sex behaviors may be particularly difficult to achieve in the context of a steady (as opposed to casual) relationship. 14
A sample of African American adolescent females was selected. Recruitment sites were located in neighborhoods characterized by high rates of unemployment, substance abuse, violence, teen pregnancy, and STDs. Recruitment sites were two adolescent medicine clinics, four health department clinics, and health classes at five high schools. As opposed to recruiting adolescents through a single venue, we selected this combination of clinics serving low-income (potentially high-risk) adolescents and schools to maximize our access to a diverse sample of adolescents. From December 1996 through April 1999, project recruiters screened 1130 female teens at these 11 sites to assess eligibility for participating in an HIV/STD prevention study. Adolescents were eligible to participate if they were African American females, 14 to 18 years old, unmarried, and sexually active in the previous 6 months. This screening procedure identified 609 eligible participants. Of those adolescents not eligible to participate in the study, the majority (98%) were not sexually active.
Eligible adolescents were informed that the study was designed to assess health risk behaviors. Of those eligible, 522 (85.7%) enrolled in the study and completed baseline assessments. Thirty-one percent of the eligible adolescents who declined to participate could not be reached to provide information about why they declined. Of the remainder, most cited conflicts with their employment schedules or lack of interest in the study as reasons for declining. Finally, chronic illness and incarceration prevented six adolescents from participating. Before implementation, the institutional review board approved the study protocol.
Data were collected at the University of Alabama at Birmingham Family Medicine Clinic. The assessment consisted of a self-administered questionnaire and a face-to-face interview conducted by trained African American female interviewers. The self-administered questionnaire was tailored at the fifth-grade reading level and administered in a group setting, with monitors providing assistance to adolescents with limited literacy. Adolescents were assured of confidentiality by being told that their names could not be linked to the codes used to identify documents containing their responses. Subsequently, adolescents completed a face-to-face interview that assessed their sexual behaviors. Young adult African American female interviewers were employed to maximize adolescents’ sense of comfort and trust with the interview. Finally, adolescents provided biological specimens for testing. Adolescents were given verbal and written instructions for the collection of urine for drug testing and vaginal swab specimens for STD testing. Adolescents were reimbursed $20.00 for their participation.
Procedures and Measures
Assessment of marijuana use.
Adolescents provided urine samples that were tested with the EMIT II assay for the presence of cannabis. 15 The Emit II assays can detect the presence of marijuana use, even very small amounts, for up to 30 days. Emit II assays are homogeneous enzyme immunoassays intended for the analysis of specific compounds in human urine. The assays are based on competition between drug in the specimen and drug labeled with the enzyme glucose-6-phosphate dehydrogenase for antibody binding sites. Enzyme activity decreases on binding to the antibody, so the drug concentration in the specimen can be measured in terms of enzyme activity. Specimen collection was conducted with standardized procedures. Emit II assays were performed at the University of Alabama at Birmingham toxicology laboratories.
Assessment of sexual behavior outcomes.
Presence of STD infection was assessed by laboratory findings. Adolescents provided two self-obtained vaginal swab specimens that were subsequently evaluated for Neisseria gonorrhoeae and Chlamydia trachomatis. 16,17 Each swab was placed in a specimen transport tube and tested for chlamydia and gonorrhea by means of a ligase-chain reaction DNA amplification assay (LCx Probe System for N gonorrhoeae and C trachomatis assays; Abbott Laboratories, Abbott Park, IL). The second swab was used to inoculate culture medium for Trichomonas vaginalis (InPouch TV test; BioMed Diagnostics, Santa Clara, CA). This culture was incubated at 37 °C and examined daily by light microscopy (magnification, ×100) for 5 days for the presence of motile trichomonads. 18 All STD assays were conducted at the University of Alabama at Birmingham Division of Infectious Diseases STD Research Laboratory.
Assessment of covariates related to the outcomes.
Identification of covariates is an important method of controlling for their potentially confounding effects. Therefore, several variables were tested as potential covariates. These variables included adolescents’ age, their current pregnancy status, their recent use of hormonal contraceptives, and their scores on a five-item scale that assessed frequency of communicating with parents about sex-related issues such as STD and pregnancy prevention (α = 0.88). Of these potential covariates, only adolescents’ current pregnancy status was associated with the key variable of interest and independently associated with the assessed outcomes and thus was included in all adjusted analyses.
Continuous variables (e.g., condom use) were assessed for normality by calculating their degree of skewness. Skewness scores exceeding an absolute value of 1.0 were considered to be an indication of a nonnormal distribution. These variables were nonnormally distributed and were subsequently dichotomized by performing a median split. Associations between laboratory-confirmed marijuana use, STDs, and condom use were assessed by calculating prevalence ratios, their 95% CIs, and corresponding P values. Logistic regression was used to calculate adjusted odds ratios, their 95% CIs, and corresponding P values, in the presence of the observed covariate.
Characteristics of the Sample
Average age of the adolescents was 16.0 years (standard deviation [SD] = 1.2 years). The majority (81.2%) were full-time students, 9.4% were part-time students, and the remainder were not enrolled in school. Fewer than one fifth (17.8%) reported having a paying job. Approximately 28% of adolescents tested positive for at least one of the three STDs assessed. The majority (81.8%) reported having sex only with a steady partner in the past 6 months, 58.1% reported consistent condom use in the past 30 days, and 53.9% reported consistent condom use in the past 6 months.
Prevalence of Marijuana Use
About two fifths (41%) reported a lifetime history of marijuana use. The average age of adolescents’ first use of marijuana was 14.5 years (SD = 1.7 years). Laboratory analysis confirmed that 28 adolescents (5.4%) had used marijuana.
Outcomes Associated With Recent Marijuana Use
Table 1 shows that, after adjustment for the covariate, adolescents with a laboratory-confirmed marijuana use were 3.4 times more likely to test positive for N gonorrhoeae and 3.9 times more likely to test positive for C trachomatis. Furthermore, adolescents with laboratory-confirmed marijuana use were 2.9 times more likely to report never using condoms in the past 30 days and 3.6 times less likely to report using condoms consistently in the past 6 months.
The findings indicate that adolescents who were laboratory-confirmed-positive for marijuana use were substantially more likely to be laboratory-confirmed-positive for gonorrhea or chlamydia. To the best of our knowledge, this is the first study to show this association based on the exclusive use of biologically assessed variables. Thus, these findings corroborate and extend the validity of previous study findings of associations between self-reported marijuana use and the presence of STDs among African American adolescents. 11,12
The findings also indicate that African American adolescent females who tested positive for marijuana were less likely to have used condoms consistently in the past 6 months and were more likely to report never having used condoms in the past 30 days. Although these associations are consistent with findings in other studies, 7–9 at least one other study has found a lack of relationship between substance use and condom use. 19 The investigators in that study suggested several reasons for this inconsistency between findings across studies, including the use of different measures of sexual behavior and potential moderators that may affect the association between substance use and condom use. These differences in measurement of sexual behaviors may partly explain the absence of an association between marijuana use and other sexual behaviors assessed in this study.
Given the high prevalence of STDs in this adolescent population and the association between marijuana use and STDs, the findings suggest that STD/HIV prevention and intervention programs should include a component addressing substance abuse, particularly marijuana use, especially because of the prevalence of its use among adolescents and its relation to risky sex and STDs. Likewise, substance-abuse treatment programs designed for this population could include a component that addresses the risk of adverse sexual health outcomes (i.e., STDs and HIV) as a consequence of substance use. These interventions need to be tailored to enhance their relevance (in developmental, gender, and cultural terms) to African American adolescent females. 20
It is not known whether marijuana use occurred immediately before engaging in risky sex or whether marijuana use is a cooccurring risk behavior. Further research should focus on determining how marijuana use affects adolescents’ sexual decision-making and, consequently, their sexual behavior. In addition, we were unable to examine the dose–response relationship between marijuana use and the outcomes, because the EMIT II assay cannot differentiate adolescents who are regular marijuana users from those who are infrequent users or merely experimenting with marijuana. Furthermore, the sample was limited to economically disadvantaged, sexually active African American adolescents. Therefore, the findings may not be generalized to other racial/ethnic groups or adolescents in different socioeconomic strata. More research is needed with diverse adolescent populations.
The findings of this study suggest an association between marijuana use and sexual risk behaviors and STDs among African American adolescent females. The exact nature of the relation between marijuana use and sexual risk behaviors is unclear. However, the findings warrant including a substance abuse component in the design and implementation of STD prevention programs that would emphasize the risk for STD acquisition and transmission associated with substance use.
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